. The depths of the ocean; a general account of the modern science of oceanography based largely on the scientific researches of the Norwegian steamer Michael Sars in the North Atlantic. Oceanography. PELAGIC PLANT LIFE 33* always occupy the whole internal space, but lies sometimes, as it were, at the bottom of a hollow hemisphere or up at the mouth-opening in a conical sac. The shields of lime can be dissolved by the weakest acids, and the cell then remains as an insignificant mass with undefined boundaries. Still, these shields are very characteristic, and have been found in such enormous qu
. The depths of the ocean; a general account of the modern science of oceanography based largely on the scientific researches of the Norwegian steamer Michael Sars in the North Atlantic. Oceanography. PELAGIC PLANT LIFE 33* always occupy the whole internal space, but lies sometimes, as it were, at the bottom of a hollow hemisphere or up at the mouth-opening in a conical sac. The shields of lime can be dissolved by the weakest acids, and the cell then remains as an insignificant mass with undefined boundaries. Still, these shields are very characteristic, and have been found in such enormous quantities in the deposits on the ocean-bottom that they aroused the attention of scientists long before the algae themselves were known. The commonest forms (Cocco- lithophora, Ponto splicer a) have an almost globular lime-covering, and are there- fore without special suspension-organs, though their surface is big in proportion to their bulk, if we consider their extra- ordinarily minute dimensions (5 to 20 /n f7 HI" (fi. Fig. 237.—Pyrocystis noctiluca. (From Chun.) Fig. 238. Pyrocystis fusiformis i1^0). (From " Challenger " Narrative.) in diameter). But in forms like Rhabdosphcera the calcareous shields have each a more or less large spike in the middle. In Discosphczra we find trumpet-shaped spines, in Scyphosphcera barrel-shaped outgrowths, and during the "Michael Sars" Expedi- tion I succeeded in discovering even stranger forms. Ophiaster has a tuft of slightly spiral flexible calcareous filaments. Michaelsarsia carries in the front of its cell a sort of parachute or pappus of hollow jointed calcareous tubes arranged in a. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Murray, John, Sir, 1841-1914; Hjort, Johan, 1869-. London Macmillan
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